﻿#include"stack.h"

//初始化栈
void StackInit(Stack* ps) {
	ps->arr = NULL;
	ps->capacity = ps->top = 0;
}

//入栈
void StackPush(Stack* ps, STDataType data) {
	//防止ps为空
	assert(ps);
	if (ps->capacity == ps->top) {
		//如果栈满则增容
		int newCapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
		STDataType* tmp = (STDataType*)realloc(ps->arr, newCapacity * sizeof(STDataType));
		if (tmp == NULL) {
			//如果申请空间失败
			perror("realloc fail");
			exit(1);
		}
		ps->arr = tmp;
		ps->capacity = newCapacity;
	}
	ps->arr[ps->top++] = data;

}

//出栈
void StackPop(Stack* ps) {
	assert(ps);
	ps->top--;
}

// 获取栈顶元素 
STDataType StackTop(Stack* ps) {
	assert(ps);
	return ps->arr[ps->top - 1];
}

// 获取栈中有效元素个数 
int StackSize(Stack* ps) {
	assert(ps);
	return ps->top;
}
// 检测栈是否为空，如果为空返回非零结果，如果不为空返回0 
int StackEmpty(Stack* ps) {
	assert(ps);
	if (ps->top == 0) {
		return 1;
	}
	else {
		return 0;
	}
}

// 销毁栈 
void StackDestroy(Stack* ps) {
	free(ps->arr);
}